1. Field of the Invention
The present invention relates generally to motorized vehicle seat back adjustment devices, in particular of the type incorporating a lead screw extending between a gear box arrangement and a pivotally associated seat back. More specifically, the present invention incorporates a reinforced and arcuate shaped catcher bracket, through which the lead screw extends, and in combination with an adjustable nut and nylon spacer bushing. The present design operates to relieve buzz, squeak and rattle conditions typically associated with such prior art gearbox arrangements in tensile loading situations and which result from free-play of the lead screw in directions in and out of the gearbox. Additionally, the present design transfers tensile and compressive loads from the gear box to the catcher bracket. This increases the fatigue life of the assembly as well as increase the amount of load the assembly is able to withstand.
2. Description of the Prior Art
The prior art is well documented with various examples of motorized powered seat back mechanisms, such as which in particular are utilized inside of a vehicle. Many such seat assemblies include the provision of a threaded lead screw and which interconnects a pivotally associated seat back with a power supplying gearbox arrangement.
A common problem encountered in such existing seatback arrangements is the existence of free-play movement (also known as endplay) of the lead screw in directions in and out of the gearbox, this directly contributing to an increase in arm looseness and deflection. In particular, the gearbox arrangement includes the provision of a plastic worm gear, seating about a periphery of the lead screw at its inserting end, and in contact with a metal drive shaft associated with an electric motor input. Free play movement of the lead screw typically results from the failure of the assembly to maintain either a separation or a constant contact between an inserted end face of the lead screw and a base abutment surface associated with the gearbox.
Other examples of prior art powered vehicle seat adjusters include such as that illustrated in U.S. Pat. No. 5,575,531, issued to Gauger et al., and which teaches a rotatable drive shaft with first and second axial ends and an intermediate arcuate portion connecting the first and second axial ends. The first and second axial ends are respectively axially connected to a drive motor gear assembly and to a driven lead screw. A horizontal drive block threadingly engaging the lead screw is rotatably and vertically translatingly mounted in an aperture in a lower track for self-alignment of the drive block with respect to the lead screw.
A housing rotatably receives the axial connection between one end of the drive shaft and the lead screw. The bearing block is rotatably and translatingly mounted in a bracket fixed to an upper track for self-alignment of the drive shaft with the lead screw. A rivet block engages the lead screw and is mounted for rotation and translation in a link. The upper and lower tracks have a guide section and an abutment section which collapse together in a self-cinching action under force loading to resist separation of the upper and lower tracks.
U.S. Pat. No. 5,203,608, issued to Tame, teaches a seat assembly with an articulating seat cushion rotatable about a transverse axis near the front end of the seat cushion. The seat back is reclinable and is coupled to the rear of the seat cushion so as to raise the rear end of the seat cushion in response to rearward reclining of the seat back, whereby the seat occupant's hip point is raised as the seat back is reclined to provide a more comfortable recliner. The recliner drive mechanism includes a lead screw with a motor/transmission assembly to drive the lead screw and includes a thrust washer carried by the lead screw to transfer axial loads on the lead screw directly to the motor mount rather than allowing the lead screw to be transferred to the internal components of the motor/transmission assembly.
U.S. Pat. No. 6,322,146, issued to Fisher, Jr., teaches a seat recliner which controllably adjusts the angular position of a seat back relative to a seat base structure and is responsive to remote actuation by an operator. The recliner includes a driven mechanism adapted to be connected to the seat back, a drive mechanism rotatable in a first and second direction, and a transmission assembly operably interconnecting the drive mechanism and the driven mechanism. The transmission assembly includes a gear retainer assembly and a mounting assembly. The mounting assembly is adapted to be connected to one of the seat base and seat back. The gear retainer assembly includes a gear housing formed of a polymeric material and adapted to accommodate the drive and driven mechanisms for operative interconnection, whereby rotation of a transmission rod in the first or second direction causes a recliner rod to move relative to the housing in a corresponding first and second linear direction.